Quenching of metastable states of antiprotonic helium atoms by collisions with H2 molecules

B. Ketzer, F. J. Hartmann, T. Von Egidy, C. Maierl, R. Pohl, J. Eades, E. Widmann, T. Yamazaki, M. Kumakura, N. Morita, R. S. Hayano, M. Hori, T. Ishikawa, H. A. Torii, I. Sugai, D. Horváth

Research output: Contribution to journalArticle

18 Citations (Scopus)


Laser resonance transitions between normally metastable states of antiprotonic helium atoms were induced making use of state dependent quenching effects caused by trace admixtures of H2 to the target helium gas. With this method of "H2-assisted inverse resonances" the decay rates of the states (n,l)=(39,l),l=36,37,38, and (38,l),l=35,36,37 of p̄He+ were determined as a function of the H2 admixture. The quenching cross sections at 30 K deduced therefrom for the states with n=39 were found to be of the order of the geometrical cross section for p̄He+-H2 collisons (2̇10-15cm2), with a moderate decrease with increasing l. Within a given cascade with constant v=n-l-1, the quenching cross sections for states with n=38 are smaller by a factor of 4-6 than those for states with n=39.

Original languageEnglish
Pages (from-to)424-431
Number of pages8
JournalJournal of Chemical Physics
Issue number2
Publication statusPublished - Dec 1 1998


ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Ketzer, B., Hartmann, F. J., Von Egidy, T., Maierl, C., Pohl, R., Eades, J., Widmann, E., Yamazaki, T., Kumakura, M., Morita, N., Hayano, R. S., Hori, M., Ishikawa, T., Torii, H. A., Sugai, I., & Horváth, D. (1998). Quenching of metastable states of antiprotonic helium atoms by collisions with H2 molecules. Journal of Chemical Physics, 109(2), 424-431. https://doi.org/10.1063/1.476579